How Can You Tell if They’re Really Key Limes?

You know those little green citrus fruits marked Key limes in supermarket bins? If the supermarket isn't in the Florida Keys, are they the real deal?

An authentic Key lime is a little yellow thing with a distinctly piney scent, knucklesandwich says on Chowhound. Even in the Keys, you can't just walk into a supermarket and buy a bag of them, not real ones, anyway.

While there are many, many varieties of limes in cultivation, there hasn't been a Key lime industry in Florida for many years, according to sunshine842. Key limes' unique combination of green flesh, yellow skin, and small size makes them unmistakable for anyone who's tried the real thing. Creole limes come close, jumpingmonk says, especially ones with pale green skins that sort of resemble unripe Keys. A true Key lime varies in size between a gumball and a walnut, though jumpingmonk has seen much larger, greener, and bumpier limes sold as Keys.

Despite rampant fakery, some Chowhounds have purchased what they believe from experience to be true Key limes. At grocery stores as far north as Tampa, Veggo has bought bags of slightly unripe greenish-yellow Key limes, perfectly spherical and smaller than a ping-pong ball, with lots of seeds. Hobbert, who's seen real Keys in Florida, has seen them at a grocery store in Northern Virginia. "Anything can be shipped," Hobbert says.

Others are skeptical. "When people talk about buying them by the bag, they probably are the Mexican ones," paulj says. And akq thinks Key limes have a lot in common with the complex taste and subtle numbing effects of Asian calamansi, often available fresh or as juice in Filipino markets.